Cladding the exterior and interior of residential and commercial buildings is gaining popularity. Exterior cladding may include a rain screen to protect the interior elements. Installation of cladding requires a framing system mounted to typically a wall of a structure, but may also be mounted to a roof, soffit, ceiling, floor, etc. The cladding is attached to the framing system. The framing system is typically made from galvanized metal. However, galvanized metal has many drawbacks.
One disadvantage is that galvanized metal cannot be used in coastal areas or areas of high moisture as the galvanized coating is insufficient to resist corrosion in these regions. Another disadvantage is that galvanized metal is difficult to cut and drill, which increases the cost and quality of the installation. Another disadvantage is that galvanized metal parts very rarely true, which requires additional labor to level components. Another disadvantage is that galvanized metal parts should be resealed after cutting or drilling to restitute the removed surface coating. Another disadvantage of conventional framing systems is that they normally provide a single-type of framing element, which must be cut and positioned to fit the geometric differences of the several structures and features (e.g., windows, doors, soffits, and corners) found on modern buildings. This one size fits all approach has proven inadequate and further increases the difficulty and cost of installation.
Another disadvantage of conventional cladding is that it fails to position the frames of the windows flush with the cladding. Windows are not normally perfectly aligned. When conventional cladding is applied, the misalignment of windows is magnified and more noticeable and thus aesthetically unpleasing. Often the window frame has a different offset than the cladding, which is also aesthetically unpleasing.
Today, there is a growing need for the use of exterior insulation in combination with exterior cladding. In a typical commercial building, the exterior walls of the building comprise vertical, metal studs. A sheathing layer is attached to the exterior of the metal studs. A water resistant barrier (WRB) may be placed over the sheathing layer. Then, a layer of vertical elements are aligned with the vertical metal studs and secured to the sheathing layer using fasteners that penetrate the sheathing layer and anchor into the metal studs. Exterior insulation is then installed over the sheathing layer and between the vertical elements. A layer of horizontal elements may be secured over the vertical elements. Lastly, cladding is secured to the horizontal elements or directly to the vertical elements when horizontal elements are not used.
Such systems have many disadvantages. One disadvantage is that the horizontal elements (which are made from metal) protrude through the exterior insulation. This creates thermal bridges that transmit heat between the outside environment and the interior of the building. These thermal bridges drastically decrease the effectiveness of the exterior insulation and thus reduce the overall energy efficiency of the building. Furthermore, such systems do not comply with more stringent building codes that require “continuous exterior insulation,” i.e., exterior insulation that is not penetrated by any sub-framing element.
Others have attempted to solve the problem of thermal bridging by attaching the framing elements to clips that penetrate the exterior insulation. Even though the use of clips reduces thermal bridging, the clip systems have many disadvantages. One disadvantage is that the clips, which must support the weight of the cladding and sub-framing system, are of substantial size and still penetrate the layer of exterior insulation. Thus, the clips still create a substantial thermal bridge. This has the further disadvantage of not complying with more stringent building codes that require continuous exterior insulation. Another disadvantage of the clips is they add another layer that increases the overall thickness of the wall. This may not be permissible where the wall already abuts the property line or reaches the setoff depth. Further, this may not be aesthetically pleasing, as windows and doors appear sunken-in. Another disadvantage is that the use of clips substantially increases the complexity of the system, thereby increasing manufacturing costs and installation costs.
Still others have attempted to solve this problem using hybrid systems. However, such hybrid systems still have many disadvantages.
One disadvantage is that such hybrid systems are not compatible with conventional sheathing boards. This makes such hybrid systems unavailable for existing structures that already have sheathing installed. Still yet another disadvantage is that such hybrid systems use vertical elements that are secured to the exterior of the hybrid boards. This requires that each vertical element must individually align with each stud in the wall, which is a laborious process that is complicated by the fact that the studs may not be true and the spacing of the studs, even within the same building, often varies.
Thus, the spacing of the vertical elements is outside the control of the designer of the sub-framing system who must ensure that sufficient vertical elements are used to support the weight of the cladding. Another disadvantage is that all sides of the vertical elements must be sealed using sealing tape because the hybrid boards have a water resistant barrier that is penetrated by the fasteners during installation. This greatly increases installation costs and time. Still another disadvantage is that such hybrid systems use galvanized metal for the vertical elements, which has all the disadvantages discussed above.
As such, there is a need for a framing system that has a greater resistance to corrosion, is simple and efficient to install, and adaptable to many different buildings and structural features. The system needs to be able to enhance the aesthetic appearance, especially of windows. Still further, there is a need for a framing system that has these advantages and is capable of being manufactured cost effectively and from low cost materials. Further, such a framing system should provide for continuous insulation.